Making and Testing Transmitter Aerials

[laanguy]

I recently made a replacement aerial for a falconry transmitter and have been asked to make some more.

My questions are;

1. The antenna is made from a 1/2 inch length of brass tube which is crimped around a 7" length of stainless wire fishing trace. This can then be threaded onto the transmitter. This seems to work well and appears the same as the original one. Is brass and stainless trace the best material or should I look to something else for better signal strength?

2. What do I need to buy and how do I test that the antenna has good signal strength. I can test an original transmitter and antenna as a guide to signal strength but want to ensure that each antenna I make is working ok and has the right signal strength.

Any advice would be apprecciated.

Andrew

[Pinecone]

Thing is, you need to test the pattern as well as the strength. I can make a antenna that will knock your socks off with signal strength, but with a beam angle of only a couple of degrees. Off that NADA.

Brass and SS will be fine. If physical strength isn't a requirement aluminum is normally used. Ultra stranded copper is probably the best stuff for flex.

Hit the ARRL site for some good books on antennas and testing them. Or talk to local hams.

[JimCob]

Andrew - You're fine as long as you duplicate the physical dimensions and materials of the original antenna as closely as possible. Your choice of conductor (brass, copper, stainless, etc) won't matter all that much but don't substitute bare wire for insulated wire or vice-versa because the insulation will affect the electrical length of the antenna.
Good luck
Jim

[Eric_N57105]

...but don't substitute bare wire for insulated wire or vice-versa because the insulation will affect the electrical length of the antenna.
Good luck
Jim

Not in any way that you could ever measure.

Eric
www.ke6us.com

[JimCob]

[QUOTE=Eric_N57105]Not in any way that you could ever measure.

Eric- Sure you could measure it! Try this test: Make a simple dipole out of 12 ga bare wire for whatever frequency you want, say 10m. Check it's resonant frequency. Then make an exact duplicate using 12 ga insulated wire and test it in the same location. Did it's resonant frequency change?

Jim N6PA

[laanguy]

The receiver that is used to track the birds has an analog gauge. When the transmitter is pulsing the receiver gauge indicates signal strength and as this strength gets higher (and the beeping sound gets stronger) it indicates the whether the receiver is pointing in the direction of the bird and whether it is getting closer.

It seems to me there must be a way to check the antennas but I thought there could be a device that showed a more accurate reading rather than using the receiver. I guess worst case is I go to the zoo and test everything with their receiver.

Thanks

[dalbert02]

These could prove useful:
http://www.mfjenterprises.com/products.php?prodid=MFJ-802
http://www.mfjenterprises.com/products.php?prodid=MFJ-259B
-dave